This invention relates to flow control valves and in particular to a shut off valve. In still greater particularity, the invention relates to a shut off valve responsive to a differential pressure between a controlled flow and a supply flow.
Shut off valves are known and utilize either manually operated mechanisms to shut off a fluid flow, or if fluid operated mechanisms are used, either an auxiliary supply of air or hydralic fluid is required or some type of fluid feed back arrangement applied to opposite ends of a valve to move the valve between open and closed positions is utilized. Such systems and valves can be relatively complicated and expensive and simplification is desirable. Although not limited thereto, one system wherein a water shut off valve according to the invention is particularly effective is a water purification system wherein water is directed through a system of filtering, conditioning, storing and piping for ultimate discharge and use, for example, by a consumer. One such system is known as a reverse osmosis system in which a supply of water is filtered and conditioned by the well known reverse osmosis process, stored in a storage tank and drawn off as needed by the user. In such systems, the filtered and treated water is stored under a pressure in a tank for use as needed. Valves, including shut off valves, are typically used to control the pressure of the conditioned water into the storage tank and, although the valve of the present invention is especially suited, adapted and is described for use in such a system, it is to be understood that the valve can be used wherever control of the pressure of one fluid is to be achieved through control of a system fluid supply.